This invention relates to a roll forming machine for producing a rain gutter and, more particularly, to an improved final forming station to insure that the formed rain gutter has a desired longitudinal curvature.
Roll forming machines for producing rain gutters are generally well known. In such a machine, the gutters are formed from a supply coil of sheet metal which is finished on a first side so that the exterior of the finished gutter has an aesthetically pleasing appearance. As the sheet metal is driven through the machine along a predetermined path of travel, its lateral profile is gradually transformed from a flat sheet into a downwardly concave trough having a desired lateral profile and with the finished side of the sheet metal forming the exterior surface of the trough. As the finished gutter exits the machine, it passes through a cutting station including a shear assembly which may be selectively activated to sever the gutter so that a desired length of finished gutter is separated from the partially finished gutter which remains in the machine. In the case where the front and back walls of the gutter do not have the same number of bends, this results in different amounts of drag on the front and back walls, causing the front and back walls to be of slightly different lengths. If the front and back walls are of different lengths, this causes the formed gutter to have longitudinal curvature. This curvature is not necessarily a bad thing. Some gutter installers prefer a longitudinal curvature where the ends of the gutter are curved toward the building on which the gutter is being installed; some installers prefer the reverse curvature; and other installers prefer no curvature. It would therefore be desirable to have a mechanism within the roll forming machine whereby the longitudinal curvature of the formed gutter can be controlled to compensate for the differential drag on the front and back gutter walls.